Abstract
The 660-km seismic discontinuity in the Earth's mantle has long been identified with the transformation of (Mg,Fe)2SiO4 from γ-spinel (ringwoodite) to (Mg,Fe)SiO3-perovskite and (Mg,Fe)O-magnesiowüstite. This has been based on experimental studies of materials quenched from high pressure and temperature1,2,3, which have shown that the transformation is consistent with the seismically observed sharpness and the depth of the discontinuity at expected mantle temperatures4. But the first in situ examination of this phase transformation in Mg2SiO4 using a multi-anvil press5 indicated that the transformation occurs at a pressure about 2 GPa lower than previously thought (equivalent to ∼600 km depth) and hence that it may not be associated with the 660-km discontinuity. Here we report the results of an in situ study of Mg2SiO4 at pressures of 20–36 GPa using a combination of double-sided laser-heating and synchrotron X-ray diffraction in a diamond-anvil cell. The phase transformation from γ-Mg2SiO4 to MgSiO3-perovskite and MgO (periclase) is readily observed in both the forward and reverse directions. In contrast to the in situ multi-anvil-press study5, we find that the pressure and temperature of the post-spinel transformation in Mg2SiO4 is consistent with seismic observations4,6 for the 660-km discontinuity.
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References
Liu, L.-G. Post-oxide phases of forsterite and enstatite. Geophys. Res. Lett. 2, 417–419 (1975).
Ito, E. & Takahashi, E. Postspinel transformations in the system Mg2SiO4–Fe2SiO4 and some geophysical implications. J. Geophys. Res. 94, 10637–10646 (1989).
Ito, E., Akaogi, M., Topor, L. & Navrotsky, A. Negative pressure-temperature slopes for reactions forming MgSiO3 perovskite from calorimetry. Science 249, 1275–1278 (1990).
Helffrich, G. Topography of the transition zone seismic discontinuities. Rev. Geophys. 38, 141–158 (2000).
Irifune, T. et al. The postspinel phase boundary in Mg2SiO4 determined by in situ X-ray diffraction. Science 279, 1698–1700 (1998).
Kennett, B. L. N., Engdahl, E. R. & Buland, R. Constraints on seismic velocities in the Earth from travel times. Geophys. J. Int. 122, 108–124 (1995).
Shim, S.-H., Duffy, T. S. & Shen, G. The stability and P–V–T equation of state for CaSiO3 perovskite in the earth's lower mantle. J. Geophys. Res. 105, 25955–25968 (2000).
Shen, G., Rivers, M. L., Wang, Y. & Sutton, S. R. Laser heated diamond cell system at the Advanced Photon Source for in situ x-ray measurements at high pressure and temperature. Rev. Sci. Instrum. 72, 1273–1282 (2001).
Holmes, N. C., Moriarty, J. A., Gathers, G. R. & Nellis, W. J. The equation of state of platinum to 660 GPa (6.6 Mbar). J. Appl. Phys. 66, 2962–2967 (1989).
Mao, H.-K., Xu, J. & Bell, P. M. Calibration of the ruby pressure gauge to 800 kbar under quasihydrostatic conditions. J. Geophys. Res. 91, 4673–4676 (1986).
Heinz, D. L. Thermal pressure in the laser-heated diamond anvil cell. Geophys. Res. Lett. 17, 1161–1164 (1990).
Fiquet, G. et al. X-ray diffraction of periclase in a laser-heated diamond-anvil cell. Phys. Earth Planet. Inter. 95, 1–17 (1996).
Kavner, A. & Duffy, T. S. Pressure-volume-temperature paths in the laser-heated diamond anvil cell. J. Appl. Phys. 89, 1907–1914 (2001).
Boehler, R. High-pressure experiments and the phase diagram of lower mantle and core materials. Rev. Geophys. 38, 221–245 (2000).
Singh, A. K. The lattice strains in a specimen (cubic system) compressed nonhydrostatically in an opposed anvil device. J. Appl. Phys. 73, 4278–4286 (1993).
Speziale, S. et al. Quasi-hydrostatic compression of magnesium oxide to 52 GPa: implications for the pressure–volume–temperature equations of state. J. Geophys. Res. 106, 515–528 (2001).
Meng, Y. et al. In situ high P–T X-ray diffraction studies on three polymorphs (α, β, γ) of Mg2SiO4. J. Geophys. Res. 98, 22199–22207 (1993).
Anderson, O. L., Isaak, D. G. & Yamamoto, S. Anharmonicity and the equation of state for gold. J. Appl. Phys. 65, 1534–1543 (1989).
Funamori, N. et al. Thermoelastic properties of MgSiO3 perovskite determined by in situ X-ray observations up to 30 GPa and 2000 K. J. Geophys. Res. 101, 8257–8269 (1996).
Jamieson, J. C., Frits, J. N. & Manghnani, M. H. in High-Pressure Research in Geophysics (eds Akimoto, S. & Manghnani, M. H.) 27–48 (Center for Academic Publications, Tokyo, 1982).
Fei, Y. Effect of temperature and composition on the bulk modulus of (Mg,Fe)O. Am. Mineral. 84, 272–276 (1999).
Dewaele, A., Fiquet, G., Andrault, D. & Häusermann, D. P–V–T equation of state of periclase from synchrotron radiation measurements. J. Geophys. Res. 105, 2869–2877 (2000).
Svendsen, B. & Ahrens, T. J. Shock-induced temperatures of MgO. Geophys. J. R. Astron. Soc. 91, 667–691 (1987).
Hirose, K. et al. In situ measurements of the phase transition boundary in Mg3Al2Si3O12: implications for the nature of the seismic discontinuities in the Earth's mantle. Earth Planet. Sci. Lett. 184, 567–573 (2001).
Anderson, O. L. The volume dependence of thermal pressure in perovskite and other minerals. Phys. Earth Planet. Inter. 112, 267–283 (1999).
Rubie, D. C. Characterising the sample environment in multianvil high-pressure experiments. Phase Transit. 68, 431–451 (1999).
Jackson, I. & Ridgen, S. M. in The Earth's Mantle: Composition, Structure, and Evolution (ed. Jackson, I.) 405–460 (Cambridge University Press, New York, 1998).
Vacher, P., Mocquet, A. & Sotin, C. Computation of seismic profiles from mineral physics: the importance of the non-olivine components for explaining the 660 km depth discontinuity. Phys. Earth Planet. Inter. 106, 275–298 (1998).
Morishima, H. et al. The phase boundary between α-Mg2SiO4 and β-Mg2SiO4 determined by in-situ X-ray observation. Science 265, 1202–1203 (1994).
van der Hilst, R. D., Widiyantoro, S. & Engdahl, E. R. Evidence for deep mantle circulation from global tomography. Nature 386, 578–584 (1997).
Kuroda, K. et al. Determination of the phase boundary between ilmenite and perovskite in MgSiO3 by in situ X-ray diffraction and quench experiments. Phys. Chem. Mineral. 27, 523–532 (2000).
Acknowledgements
We thank S. Speziale for experimental assistance, and F. Dahlen, T. Irifune, Y. Fei, O. Anderson and I. Jackson for discussions. This work was supported by the NSF.
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Shim, SH., Duffy, T. & Shen, G. The post-spinel transformation in Mg2SiO4 and its relation to the 660-km seismic discontinuity. Nature 411, 571–574 (2001). https://doi.org/10.1038/35079053
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DOI: https://doi.org/10.1038/35079053
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